Process and apparatus for forming annular corrugations in metal tubing

ABSTRACT

A process and apparatus for forming annular corrugations in metal tubing, wherein a pair of corrugating die holders each carrying a corrugating die, are arranged in tandem relation; the metal tubing moving longitudinally for successive engagement of the corrugating dies therewith to form successive sets of corrugations in the tubing, the corrugations of one set of corrugations alternating with corrugations of the other set of corrugations, whereby to maximize the speed of production of the corrugated tubing.

United States Patent [191 Martin PROCESS AND APPARATUS FOR FORIVHNG ANNULAR CORRUGATIONS IN METAL TUBING [75] Inventor: Helmut Martin, Hannover, Germany 7 [73] Assignee: Kabel-und Metallwerke Gutehoffnungshutte Aktiengesellschaft, Hannover, Germany 221 Filed: Dec. 2, 1971 21 Appl. No.: 203,953

[30] Foreign Application Priority Data Dec. 5, 1970 Germany 2060024 [52] US. Cl. 72/77 [51] Int. Cl B21d 15/06,

[58] Field of Search 72/77, 78, 115, 123, I02

[56] References Cited UNITED STATES PATENTS I Holdup et alr 72/77 [1-1] 3,788,113 Jan. 29, 1974 3,464,250 9/1969 Stetka 72/77 3,543,551 12/1970 Raisch et al. 72/77 3,656,331 4/l972 Kuypers et a1... 72/77 3/1934 Dreyer 72/102 Primary Examiner-Richard J. l-lerbst Attorney, Agent, or Firm-Philip G. Hilbert 5 7] ABSTRACT A process and apparatus for forming annular corrugations in metal tubing, wherein a pair of corrugating die holders each carrying a corrugating die, are arranged in tandem relation; the metal tubing moving longitudinally for successive engagement of the corrugating dies therewith to form successive sets of corrugations in the tubing, the corrugations of one set of corrugations alternating with corrugations of the other set of corrugations, whereby to maximize the speed of production of the corrugated tubing.

4 Claims, 3 Drawing Figures PROCESS AND APPARATUS FOR FORMING ANNULAR CORRUGATIONS IN METAL TUBING BACKGROUND OF THE INVENTION nally transporting smooth walled tubing through a rotating corrugating die suitably mounted in a die holder arranged for adjustable disposition in respect to the longitudinal axis of the tubing.

The rate of production of corrugated tubing made in accordance with the aforesaid application, is somewhat limited, particularly with tubing oflarger diameters and relatively harder metal.

Accordingly, an object of this invention is to provide an improved process and apparatus for forming annular corrugations in tubing in a continuous manner and at increased production rates compared to that set forth in said application. Ser. No. 22,787.

Another object of this invention is to provide an improved process and apparatus of the character described, wherein a pair of currugating die holders, each carrying an annular corrugating die, are disposed in successive tandem arrangement with the tubing moving longitudinally therethrough, one of the dies being rotated to form suitably spaced annular corrugations, the other die also being rotated to form annular corrugations in the spaces between the first mentioned corrugations.

A further object of this invention is to provide an improved process and apparatus of the character described wherein for a given rotational speed of the die holders, the rate of movement of the tubing may be increased, thereby increasing production rates for the given rotational speed of the die holders.

Still another object of this invention is to provide an improved process and apparatus of the character described wherein the die holders and their dies are disposed in separate corrugating units, the units being arranged in tandem relation and suitably correlated to form the two sets of interrelated corrugations; alternatively, the die holders and their dies being diposed in a single corrugating unit, in tandem relation.

Yet another object of this invention is to provide an improved process and apparatus of the character described, wherein the corrugating dies are eccentrically related to the axis of the tubing; the effective die portions of the dies being angularly out of phase whereby to neutralize incident stresses.

Other objects of this invention will in part be obvious and in part hereinafter pointed out.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing the details of apparatus for producing annular corrugations in a tubing, in accordance with the invention;

FIG. 2 is a top plan view showing a portion of one adjustment means for the corrugating die assembly; and

FIG. 3 is a top plan view showing another adjustment means for the corrugating die assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring in detail to the drawing, and particularly to FIG. 1, 12 designates corrugating, means for forming annular corrugations in tubing of copper, steel or other suitable metal, generally indicated at A, the successive corrugations being indicated at B at the right hand end of corrugating means 12.

Tubing A is transported longitudinally through corrugating means by known transport means, such as that shown in U.S. Pat. No. 3,085,729 or U.S. Pat. No. 3,656,331.

Corrugating means 12 comprises a rotatable annular housing 21 open at one end thereof and which is suitably connected for rotation, as by rotating means shown in U.S. Pat. No. 3,656,331. The corrugating means 12 is adapted to pass tubing A axially therethrough for the purpose of impressing successive annular corrugations therein.

Corrugating means 12 comprises a bushing 26 to which the annular housing 21 is suitably attached. Concentrically located in bushing 26 is a sleeve 27; the housing 21 and bushing 26 'being rotatable relative to sleeve 27 with bearing 27A disposed therebetween.

A collar 28 is mounted on the inner surface of sleeve 27 and carries a guide sleeve 29, said guide sleeve 29, collar 28 and sleeve 27 being held together by a screw 29A. The tubing A passes axially through guide sleeve 29; the forward edge 29B thereof supporting tubing A as the same is presented to the corrugating means and taking up the torque incident to the corrugating operation. The longitudinally moving tubing A is thus presented to a first corrugating assembly generally indicated at .30, which assembly is mounted within housing 21.

Corrugating assembly 30 comprises an annular corrugating die 31 which is mounted on the inner annular bearing member 32 concentrically positioned within outer annular bearing member 33, with ball bearings 34 therebetween.

The die 31 is mounted on the inner side of the inner bearing member 32 by way of an annular shoulder 35 projecting radially inward and a split ring 36 received in an annular slot 37 formed on the inner surface of bearing member 33. It is understood that die 31 'may be readily separated from bearing member 23 by removing split ring 36, for the purpose of replacing the same with other selected die members for forming annular corrugations of selected dimensions and configurations. Die 31 comprises an annular portion 38 having a helical rib portion 39 extending radially inward thereof, and shown in greater detail in U.S. Pat. No. 3,656,331.

In order that die member 31 be operative to impress successive corrugations in tubing A, it has been found that the corrugating assembly 30 must be disposed in tilted relation to the longitudinal axis of housing 21. To this end, the assembly 30 is provided with journal shafts 45, 46 extending radially and outwardly from the outer bearing member 33. Said journal shafts 45, 46 being received in diametrically opposed bearing openings 47, 48 respectively formed in housing 21.

Means is provided for adjustably moving said assembly 30 by way of journal shafts 45, 46 to selected angular positions, to this end, the journal shaft 45 has the outer end portion thereof square cross section as at 45A, said portion 45A projecting through a circular opening in a plate 49 fixed to the outer surface of housing 21.

A shifting plate 50 having a square opening 51 for passing shaft portion 45A therethrough, is movably mounted on plate 49 by locking screws 52 passing through opposed arcuate slots 53 formed in plate 50. It will be apparent that by use of a suitable tool and engaging shaft portion 45A, the assembly 30 may be angularly displaced to selected tilted positions and retained in such positions by means of locking screws 52.

As the central axis of corrugating assembly 30 must be displaced with respect to the longitudinal axis of the housing 21, so that the corrugating rib portion 39 may engage an impress the annular corrugations in tubing A with a rolling movement; said assembly 30 is arranged for axial movement relative to housing 21, by way of shafts 45, 46.

To this end, the upper journal shaft 46 is formed with an axial, internally threaded recess 54 for receiving a screw member 55 having a radial flange 56. A circuit recessed plate 57 is fixed to the outer surface of housing 21 and has a circular opening for passing screw member 55 and seating flange 56. A plate 58 having a circular opening 59 for passing the outer end 55A of screw 55 is fixed to plate 57 by screws 60. The outer end portion of screw 55 being of square cross-section to allow the application of a tool thereto for rotating the same end thereby axially moving said assembly 30 to selected positions wherein the central axis XX thereof is displaced from the longitudinal axis Y--Y of the housing 21 by a predetermined distance Z. Thus, such adjustment will determine the depth of the annular corrugations formed in tubing A.

It is understood that the corrugating assembly 30 functions as set forth in said application Ser. No. 22,787; except that suitable adjustments are made such that successive corrugations C are spaced from each other to provide uncorrugated portions D therebetween.

A second corrugation assembly 30A is mounted in housing 21 and in tandem relation to the first assembly 30. The assembly 30A comprises the constituent parts corresponding to parts in assembly 30. However, assembly 30A is adjusted with respect to assembly 30, so as to form corrugations E in the uncorrugated portions D of tubing A. Thus, corrugations E alternate with corrugations C tof form successive annular corrguations B, as indicated in the output side of housing 21.

It has been found that with the tandem arrangement of corrugation assemblies 30, 30A, the rate of forming corrugations in tubing A maybe substantially increased without changing the rotational speed of the assemblies.

Further, the assembly 30A is arranged relative to assembly 30, so that the rib portions 39 thereof are angularly out of phase and preferably at 180 from each other; thereby neutralizing the stresses incident to the corrugating operation.

Also, a pair of successive corrugation assemblies 30 may be used to first form corrugations C of less then desired depth; the second assembly 30 being operative to increase the depth of the incomplete corrugations C to a desired depth. This is particularly effective when corrugating tubing A of hard metal. Similarly a pair of assemblies 30A are used to form corrugations E in two steps.

Preferably, corrugation assemblies 30, 30A are adjusted so that corrugations E and C are entirely similar as to depth and configuration, so that final corrugations B are all uniform. However, it will be apparent that by suitable adjustment of assemblies 30, 30A, the altemating corrugations E and C may differ as to depth and configuration.

It is understood that the helical rib portion 39 has a pitch correlated to the number of corrugating dies used and the desired distance between the annular corrugations.

1 claim:

1. Apparatus for continuously forming annular corrugations in tubing, said apparatus comprising an annular housing arranged for rotation about the axis thereof, first corrugating means rotatably mounted in said housing and second corrugating means rotatably mounted in said housing and located in axially spaced relation to said first corrugating means, each of said corrugating means comprising an annular die holder and annular corrugating die means mounted in the die holder, means on said housing engageable with each of said die holders for adjustably locating said holders in selected positions eccentrically related to the axis of said housing, whereby said first corrugating means is position to form a first set of annular corrugations in said tubing spaced to provide uncorrugated wall portions of said tubing between successive corrugations, and said second corrugating means is positioned to form a second set of corrugations in the uncorrugated wall portions of said tubing.

2. Apparatus as in claim 1 wherein each of said corrugating die means comprises an annular member and a helical corrugating rib on an inner edge portion thereof.

3. Apparatus as in claim 1, wherein said adjustable mounting means further comprises means for angulai'ly displacing said holder means about a radial axis thereof.

4. Apparatus as in claim 1 wherein said first and second holder means have different axial displacements with respect to the said axis of saidhousing means whereby to dispose one of said corrgating die means in an out of phase relation to the other of said corrugating die means. 

1. Apparatus for continuously forming annular corrugations in tubing, said apparatus comprising an annular housing arranged for rotation about the axis thereof, first corrugating means rotatably mounted in said housing and second corrugating means rotatably mounted in said housing and located in axially spaced relation to said first corrugating means, each of said corrugating means comprising an annular die holder and annular corrugating die means mounted in the die holdEr, means on said housing engageable with each of said die holders for adjustably locating said holders in selected positions eccentrically related to the axis of said housing, whereby said first corrugating means is position to form a first set of annular corrugations in said tubing spaced to provide uncorrugated wall portions of said tubing between successive corrugations, and said second corrugating means is positioned to form a second set of corrugations in the uncorrugated wall portions of said tubing.
 2. Apparatus as in claim 1 wherein each of said corrugating die means comprises an annular member and a helical corrugating rib on an inner edge portion thereof.
 3. Apparatus as in claim 1, wherein said adjustable mounting means further comprises means for angularly displacing said holder means about a radial axis thereof.
 4. Apparatus as in claim 1 wherein said first and second holder means have different axial displacements with respect to the said axis of saidhousing means whereby to dispose one of said corrgating die means in an out of phase relation to the other of said corrugating die means. 